A SGWB is formed by the incoherent superposition of plenty of unresolved GW [1]}, [2]}, [3]}.
Especially, SGWB will become foreground when exceeding the detector noise level [4]}, [5]}.
The origin of SGWB can be generally divided into astrophysics and cosmology [6]}, [7]}.
The astrophysical-origin contains nearby objects, among which the Galactic DWD is predicted to produce an anisotropic foreground [8]}, [9]}.
The cosmological-origin is related to the physical processes of the early Universe,
and the cosmological SGWB is generally considered to be highly isotropic unless there is a specific physical mechanism [10]}.
